1. Technical Field
The present invention relates to control apparatuses for liquid ejecting heads, liquid ejecting apparatuses, and control methods for liquid ejecting heads that eject a liquid through nozzles.
2. Related Art
In recent years, ink jet recording apparatuses such as ink jet printers, plotters, and the like, which print images and so on by ejecting ink droplets onto paper, are being widely used as liquid ejecting apparatuses that eject liquid droplets onto a target. In an ink jet recording apparatus, printing is carried out by moving a recording head in the main scanning direction while moving the paper in the sub scanning direction. Specifically, the recording head and an ink cartridge are mounted in a carriage, and the carriage is then moved in the main scanning direction. Nozzle rows, in which nozzles are arranged in rows, are formed in the bottom surface of this type of recording head, and the ink cartridge and the nozzles are connected to each other through a flow channel. In other words, ink flows from the ink cartridge, through the flow channel, and to the nozzle rows.
A printer that includes first and second ink cartridges holding the same color of ink, a first flow channel that connects the first ink cartridge with a first nozzle row, and a second flow channel that connects the second ink cartridge with a second nozzle row, is known as this type of ink jet recording apparatus (see JP-A-2003-1842). The nozzles in the first nozzle row and the nozzles in the second nozzle row are disposed in positions that are skewed relative to each other in the sub scanning direction (that is, the paper feed direction). Accordingly, it is possible to print two lines worth of dots simultaneously by ejecting ink from the first and second nozzle rows simultaneously. Furthermore, this printer includes a remaining ink estimation unit that detects the amount of ink remaining in the first and second ink cartridges, and a selection unit that selects the ink cartridge to use to form dots based on the remaining amount of ink.
However, with an ink jet printer that includes first and second ink cartridges holding the same color of ink, as is the case with the printer according to JP-A-2003-1842, if the ink in one of the ink cartridges is exhausted, printing may be suspended partway through the page that is currently being printed.
If the printing is suspended partway through the page in this manner, it is necessary to resend the print data to the printer after replacing the ink cartridge and then resume printing from the beginning of the page in which the printing was suspended; this is a problem not only in that time and effort are required, but also in that paper, ink, and so on are wasted.
Although continuing the printing from the location at which the printing was suspended using only the ink cartridge in which ink still remains can be considered, such a method is unrealistic because a difference in color between the areas printed after the printing is resumed and the areas printed before the suspension can arise, leading to a drop in the quality of the print.
It should be noted that this problem is not limited to ink jet printers that eject ink, and also appears in the same manner in liquid ejecting apparatuses that eject other liquids.